Photocurable composition, method for forming a pattern, and method for producing a photocured product

ABSTRACT

It is intended to provide a photocured product that is prepared using the photo-imprint method and has favorable pattern precision and improvement in pattern defects. The present invention provides a photocured product obtained by irradiating a coating film in contact with a mold with light, the photocured product containing a fluorine atom-containing surfactant, wherein of secondary ion signals obtained by the surface analysis of the photocured product based on time-of-flight secondary ion mass spectrometry, the intensity of a C 2 H 5 O 30  ion signal is higher than that of a C 3 H 7 O +  ion signal.

TECHNICAL FIELD

The present invention relates to a photocured product and a method forproducing the same.

Background Art

In recent years, semiconductor integrated circuits have been renderedfiner and more integrated.

Photolithography is frequently used as a patterning technique forsemiconductors. Finer patterns based on the photolithography, however,cannot go beyond the diffraction limit of exposing light.

Thus, a nanoimprint method has been proposed for further promoting finerand higher precision circuits. The nanoimprint method refers to a thinfilm patterning technique that involves pressing a mold having a fineelevation/depression pattern against a substrate coated with a thinresin film to transfer the elevation/depression pattern in the mold tothe thin resin film coating the substrate.

Among the nanoimprint methods, a photo-nanoimprint method disclosed in,for example, NPL 1 has received attention. The photo-nanoimprint methodinvolves: impressing a mold transparent to exposing light onto aphotocurable composition coating a substrate; curing the photocurablecomposition by light irradiation; and demolding the mold from theresulting cured product to produce a fine resist pattern-integratedsubstrate.

However, some problems should be solved for using the photo-nanoimprintmethod. One of the problems is that force required for releasing a moldfrom a cured product, i.e., mold release force, is large. Due to thislarge mold release force, the photo-nanoimprint method has disadvantagessuch as pattern defects and the reduced precision of alignment between amold and a substrate resulting from the coming off of the substrate fromthe stage.

In response to such problems, PTL 1 discloses a photocured product forimprint, including a deep part disposed on the substrate side and asurface part disposed on the deep part, the surface part having a highercontent of a fluorine compound than that of the deep part.Alternatively, PTL 2 discloses a photocurable composition forphoto-imprint, including at least one polymerizable monomer, aphotopolymerization initiator, and a fluorine atom-containingsurfactant.

The photocured product disclosed in PTL 1 is intended to decreasesurface energy by means of the fluorine compound contained in thesurface part, thereby reducing mold release force produced during thedemolding of a mold from the photocured product. Also, PTL 2 is intendedto reduce mold release force under principles similar to those of PTL 1using the photocurable composition containing the fluorineatom-containing surfactant. Unfortunately, the photocurable resincompositions disclosed in PTL 1 and PTL 2 are not sufficiently effectivefor reducing the mold release force.

CITATION LIST Patent Literature

PTL 1: Japanese Patent Application Laid-Open No. 2006-080447

PTL 2: Japanese Patent Application Laid-Open No. 2007-084625

Non Patent Literature

NPL 1: Proc. SPIE 3676, Emerging Lithographic Technologies III, P. 379,1999

SUMMARY OF INVENTION

The present invention has been made to solve the problems of theconventional techniques, and an object of the present invention is toprovide a photocured product that is prepared using the photo-imprintmethod and has favorable pattern precision and improvement in patterndefects.

The photocured product of the present invention is a photocured productobtained by irradiating a photocurable composition in contact with amold with light,

the photocured product containing a fluorine atom-containing surfactant,wherein

of secondary ion signals obtained by the surface analysis of thephotocured product based on time-of-flight secondary ion massspectrometry, the intensity of a C₂H₅O³⁰ ion signal is higher than thatof a C₃H₇O⁺ ion signal.

The photocured product of the present invention requires only small moldrelease force for demolding a mold from the photocured product. Thepresent invention can therefore provide a photocured product that isprepared using the photo-imprint method and has favorable patternprecision and improvement in pattern defects.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A, 1B, 1C, ID, IE and IF are a cross-sectional view schematicallyillustrating one example of a production process for the photocuredproduct of the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the embodiments of the present invention will be describedappropriately in detail with reference to the drawings. However, theembodiments described below are to be considered in all respects to beillustrative only and not restrictive. Appropriate changes,modifications, etc. may be made in the embodiments described below basedon the common knowledge of those skilled in the art without departingfrom the spirit of the present invention and may be included in thescope of the present invention.

Photocured Product

First, the photocured product of the present invention will bedescribed. The photocured product of the present invention is obtainedby irradiating a coating film in contact with a mold with light. In thepresent invention, the coating film formed for producing the photocuredproduct of the present invention can be a thin film formed by coating asubstrate or the like with a photocurable composition described later.

The photocured product of the present invention has the followingfeatures (a) and (b):

(a) the photocured product contains a fluorine atom-containingsurfactant; and

(b) of secondary ion signals obtained by the surface analysis (of thephotocured product) based on time-of-flight secondary ion massspectrometry, the intensity of a C₂H₅O³⁰ ion signal is higher than thatof a C₃H₇O⁺ ion signal.

The present inventors have found that mold release force produced duringthe demolding of a mold from the photocured product can be reduced bysatisfying the requirements (a) and (b).

Hereinafter, the photocured product of the present invention will bedescribed in detail.

(1) Photocured Product

The photocured product of the present invention is a polymer compoundobtained by light irradiation. Specifically, the photocured product ofthe present invention is produced from a photocurable compositioncontaining: a compound that forms a radical or a cation throughphotochemical reaction (photopolymerization initiator); and apolymerizable monomer. The details of the photocurable composition willbe described later.

(2) Fluorine Atom-containing Surfactant

The fluorine atom-containing surfactant contained in the photocuredproduct of the present invention is distributed mainly in the surface ofthe photocured product of the present invention and plays a role inreducing mold release force produced during the demolding of thephotocured product of the present invention from a mold.

In the present invention, the fluorine atom-containing surfactant can becontained, for example, in the following aspects (i) to (iii), in thephotocured product:

(i) the aspect in which the fluorine atom-containing surfactant iscontained therein as one component of the photocurable composition;

(ii) the aspect in which a mold surface-coated with the fluorineatom-containing surfactant is contacted with a photocurable compositionfree from the fluorine atom-containing surfactant so that the fluorineatom-containing surfactant is transferred to the photocurablecomposition before light irradiation; and

(iii) the aspect in which a mold surface-coated with the fluorineatom-containing surfactant is contacted with a photocurable compositionfree from the fluorine atom-containing surfactant and irradiated withlight to transfer the fluorine atom-containing surfactant to thephotocured product.

In this context, in the case of using the mold surface-coated with thefluorine atom-containing surfactant as in the aspect (ii) or (iii),repeated imprints may cause the fluorine atom-containing surfactantcoating the surface of the mold to gradually come off the surface. Bycontrast, in the case of using the fluorine atom-containing surfactantcontained in the photocurable composition as in the aspect (i), thefluorine atom-containing surfactant is constantly supplied to the moldand the photocured product even during repeated imprints. Thus,excellent repetition durability is obtained in this aspect. Of theaspects (i) to (iii), the aspect (i) is preferred.

(3) Surface Analysis of Photocured Product Based on TOF-SIMS

TOF-SIMS is an analysis method for examining the types of atoms ormolecules present on the surface of a solid sample. Hereinafter, theoutline of this method will be described briefly.

Upon irradiation with a fast ion beam pulse (primary ions) in highvacuum, solid sample surface generates positively or negatively chargedions (secondary ions) by a sputtering phenomenon and releases thesesecondary ions in vacuum. These secondary ions are allowed to convergein one direction by an electric field and detected at a position somedistance therefrom. The sample surface generates various secondary ionsdiffering in mass according to the composition of the sample surface.Lighter ions fly faster whereas heavier ions fly slower. Thus, themasses of the generated secondary ions can be analyzed by measuring thetime from the generation of the secondary ions to their detection (timeof flight). Upon irradiation with the primary ions, the solid samplereleases, in vacuum, only the secondary ions generated in the outermostsurface of the solid sample. Thus, information about the surface(approximately several nm deep) of the sample can be obtained.

The obtained data is a mass spectrum in which m/z (m: secondary ionmass, z: charge ratio) is plotted in the abscissa against the numbers ofcounts of the detected ions in the ordinate. In this context, the massof a secondary ion is determined from the position of the signal(hereinafter, also referred to as a peak) of the secondary ion on theabscissa of this mass spectrum. The element composition of the secondaryion is determined from this mass. At the same time, the signal intensityof the secondary ion can be evaluated from the height or area of thepeak in the mass spectrum.

Most of the secondary ions obtained in TOF-SIMS are fragment ions formedby the decomposition of molecular structures (fragmentation)accompanying primary ion irradiation. Of the formed fragment ions, ionshaving hydrogen (H), carbon (C), and oxygen (O) can serve as origins ofvarious organic compounds. Fragment ions that reflect the substructureof an organic compound present mainly in sample surface tend to beobtained as peaks having high signal intensity. Thus, the elementcomposition and signal intensities of the secondary ions formed asfragment ions can be measured and evaluated, thereby predicting thesubstructures or species of molecules present mainly in the surface ofthe photocured product.

The fragment ions that are important for the present invention are aC₂H₅O³⁰ ion (m/z=45) and a C₃H₇O⁺ ion ion (m/z=45) and a C₃H₇O⁺ ion(m/z=59). The possible source of generation of the C₂H₅O³⁰ ion is mainlya compound containing ethylene oxide (—CH₂CH₂O—) as a repeating unit orthe like in the substructure. On the other hand, the possible source ofgeneration of the C₃H₇O⁺ ion is mainly a compound containing propyleneoxide (—CH₂CH₂CH₂O—) as a repeating unit or the like in thesubstructure. In this context, a feature of the photocured product ofthe present invention is that of fragments obtained by TOF-SIMS, theC₂H₅O⁺ ion is larger in number than the C₃H₇O⁺ ion. This means that thesurface portion of the photocured product mainly has ethylene oxide(—CH₂CH₂O—) , not propylene oxide (—CH₂CH₂CH₂O—). However, this does notmean that the substructure of the surface of the photocured product,which serves as an origin of the C₂H₅O⁺ ion, is occupied by ethyleneoxide (—CH₂CH₂O—).

In this context, the compound having ethylene oxide (—CH₂CH₂O), which isthe main source of generation of the C₂H₅O⁺ ion in the photocuredproduct of the present invention, may be the polymer compound on whichthe photocured product is based, or the fluorine atom-containingsurfactant.

The precise reason why particularly the fluorine atom-containingsurfactant having ethylene oxide can be used in the present inventionremains to be elucidated. However, some hypotheses can be made from theviewpoint of the affinity of the substructure containing ethylene oxideor other substructures for compound molecules other than the fluorineatom-containing surfactant. The possible hypotheses are as described in,for example, the following (i) to (iii):

(i) First Hypothesis

A first possible hypothese is that: since ethylene oxide has loweraffinity for a fluorine atom than that of propylene oxide, an interfaceis formed between ethylene oxide and the fluorine atom in the fluorineatom-containing surfactant attached on the mold side so that theaffinity therebetween is further reduced to reduce mold release force.

(ii) Second Hypothesis

A second possible hypothesis is that: since ethylene oxide has loweraffinity for a polymerizable monomer than that of propylene oxide, thefluorine atom-containing surfactant structurally containing ethyleneoxide has a higher surface segregation effect and consequently promotesthe effect of reducing mold release force by fluorine.

(iii) Third Hypothesis

A third possible hypothesis is that: since ethylene oxide has higheraffinity for quartz than that of propylene oxide, the fluorineatom-containing surfactant structurally containing ethylene oxide iseasily attached to mold surface by the photo-imprint method describedlater and consequently promotes the effect of reducing mold releaseforce by fluorine.

(3) TOF-SIMS Measurement

Next, the TOF-SIMS measurement method will be described.

A general liquid metal ion such as Ga⁺ as well as a cluster ion such asAu₃ ⁺ or Bi₃ ⁺ can be used as a primary ion species in the TOF-SIMSmethod from the viewpoint of ionization efficiency, mass resolution,etc. However, in the present invention, the primary ion used in theTOF-SIMS measurement is not limited to these ions.

Suitable analysis conditions for the TOF-SIMS measurement can be definedneither easily nor univocally. Typical conditions will be describedbelow. Specifically, the primary ion pulse frequency ranges from 1 kHzto 50 kHz; the primary ion beam energy ranges from 12 keV to 25 keV; andthe primary ion beam pulse width ranges from 0.5 ns to 10 ns. In thecase of an insulator sample, the surface of the sample may beneutralized with electron beam. 16 to 512 repetitive scans of theprimary ion beam in a measurement area of 10 μm to 500 μm square can beperformed with a pixel area of 64 to 512 pixels square, therebysimultaneously obtaining the mass spectrum of the measurement area andthe secondary distribution image of the secondary ions.

The signal intensity of each ion obtained by the TOF-SIMS measurementcan be calculated as the height or area of a selected peak positioned atthe desired m/z from the obtained mass spectrum.

In the present invention, the respective signal intensities of at leastthe C₂H₅O⁺ ion (m/z=45) and the C₃H₇O⁺ ion (m/z=59) are calculated.

In the present invention, the signal intensity of a secondary ion otherthan the C₂H₅O⁺ ion and the C₃H₇O⁺ ion may be calculated. For example,the signal intensity of an F⁺ ion (m/z=19) may also be calculated forthe purpose of confirming that the fluorine group of the fluorineatom-containing surfactant is present in the surface. Also, in the caseof using a (meth)acrylic acid compound as a polymerizable monomer, thesignal intensity of a C₃H₃O⁺ ion (m/z=55) may be calculated for thepurpose of confirming that an acrylic group is present in the surface ofa photopolymerization product.

The TOF-SIMS measurement described above can be carried out for aplurality of regions in consideration of the in-plane distribution ofsample surface, and an average of the obtained values can be determined.

Alternatively, the whole surface of the sample may be assayed in a stageraster measurement mode to calculate the signal intensity thereof.

Photocurable Composition

Next, the photocurable composition of the present invention will bedescribed. The photocurable composition of the present invention has atleast a polymerizable monomer, a photopolymerization initiator, and afluorine atom-containing surfactant. Hereinafter, each componentcontained in the photocurable composition will be described.

(1) Polymerizable Monomer (Component A)

Examples of the polymerizable monomer (component A) contained in thephotocurable composition of the present invention includeradical-polymerizable monomers and cation-polymerizable monomers.

(1-1) Radical-polymerizable Monomer

Specifically, a compound having one or more acryloyl groups (CH₂═CHCOO—)or methacryloyl groups (CH₂═C(CH₃) COO—) can be used as aradical-polymerizable monomer.

Examples of the monofunctional (meth)acrylic compound having oneacryloyl group or methacryloyl group include, but not limited to,phenoxy ethyl (meth)acrylate, phenoxy-2-methylethyl (meth)acrylate,phenoxy ethoxyethyl (meth)acrylate, 3-phenoxy-2-hydroxypropyl(meth)acrylate, 2-phenylphenoxy ethyl (meth)acrylate, 4-phenylphenoxyethyl (meth)acrylate, 3-(2-phenylphenyl)-2-hydroxypropyl (meth)acrylate,(meth)acrylate of p-cumylphenol reacted with ethylene oxide,2-bromophenoxy ethyl (meth)acrylate, 2,4-dibromophenoxy ethyl(meth)acrylate, 2,4,6-tribromophenoxy ethyl (meth)acrylate, phenoxy(meth)acrylate modified with two moles or more of ethylene oxide orpropylene oxide, polyoxyethylene nonylphenyl ether (meth)acrylate,isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate,2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate,bornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentanyl(meth)acrylate, dicyclopentenyl (meth)acrylate, cyclohexyl(meth)acrylate, 4-butylcyclohexyl (meth)acrylate, acryloylmorpholine,2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,2-hydroxybutyl (meth)acrylate, methyl (meth)acrylate, ethyl(meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl(meth)acrylate, amyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl(meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl(meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl(meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl(meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl(meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate,isostearyl (meth)acrylate, benzyl (meth)acrylate, tetrahydrofurfuryl(meth)acrylate, butoxyethyl (meth)acrylate, ethoxy diethylene glycol(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropyleneglycol mono(meth)acrylate, methoxy ethylene glycol (meth)acrylate,ethoxyethyl (meth)acrylate, methoxy polyethylene glycol (meth)acrylate,methoxy polypropylene glycol (meth)acrylate, diacetone (meth)acrylamide,isobutoxy methyl (meth)acrylamide, N,N-dimethyl(meth)acrylamide,t-octyl(meth)acrylamide, dimethylaminoethyl (meth)acrylate,diethylaminoethyl (meth)acrylate, 7-amino-3,7-dimethyloctyl(meth)acrylate, N,N-diethyl(meth)acrylamide, andN,N-dimethylaminopropyl(meth)acrylamide.

Of the compounds described above, examples of the commercially availablemonofunctional (meth)acrylic compound include, but not limited to,Aronix M101, M102, M110, M111, M113, M117, M5700, TO-1317, M120, M150,and M156 (all manufactured by Toagosei Co., Ltd.), MEDOL10, MIBDOL10,CHDOL10, MMDOL30, MEDOL30, MIBDOL30, CHDOL30, LA, IBXA, 2-MTA, HPA, andBiscoat #150, #155, #158, #190, #192, #193, #220, #2000, #2100, and#2150 (all manufactured by Osaka Organic Chemical Industry, Ltd.), LightAcrylate BO-A, EC-A, DMP-A, THF-A, HOP-A, HOA-MPE, HOA-MPL, PO-A,P-200A, NP-4EA, and NP-8EA, and epoxy ester M-600A (all manufactured byKyoeisha Chemical Co., Ltd.), KAYARAD TC110S, R-564, and R-128H (allmanufactured by Nippon Kayaku Co., Ltd.), NK ester AMP-10G and AMP-20G(all manufactured by Shin-Nakamura Chemical Co., Ltd.), FA-511A, 512A,and 513A (all manufactured by Hitachi Chemical Co., Ltd.), PHE, CEA,PHE-2, PHE-4, BR-31, BR-31M, and BR-32 (all manufactured by Dai-IchiKogyo Seiyaku Co., Ltd.), VP (manufactured by BASF), and ACMO, DMAA, andDMAPAA (all manufactured by Kohjin Holdings Co., Ltd.).

Examples of the polyfunctional (meth)acrylic compound having two or moreacryloyl groups or methacryloyl groups include, but not limited to,trimethylolpropane di(meth)acrylate, trimethylolpropanetri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate,PO-modified trimethylolpropane tri(meth)acrylate, EO,PO-modifiedtrimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate,pentaerythritol tetra(meth)acrylate, ethylene glycol di(meth)acrylate,tetraethylene glycol di(meth)acrylate, polyethylene glycoldi(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,4-butanedioldi(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycoldi(meth)acrylate, tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate,tris(acryloyloxy) isocyanurate, bis(hydroxymethyl)tricyclodecanedi(meth)acrylate, dipentaerythritol penta(meth)acrylate,dipentaerythritol hexa(meth)acrylate, EO-modified2,2-bis(4-((meth)acryloyloxy)phenyl)propane, PO-modified2,2-bis(4-((meth)acryloyloxy)phenyl)propane, and EO,PO-modif ied2,2-bis(4-((meth)acryloyloxy)phenyl)propane.

Of the compounds described above, examples of the commercially availablepolyfunctional (meth)acrylic compound include, but not limited to,Yupimer UV SA1002 and SA2007 (all manufactured by Mitsubishi ChemicalCorp.), Biscoat #195, #230, #215, #260, #335HP, #295, #300, #360, #700,GPT, and 3PA (all manufactured by Osaka Organic Chemical Industry,Ltd.), Light Acrylate 4EG-A, 9EG-A, NP-A, DCP-A, BP-4EA, BP-4PA, TMP-A,PE-3A, PE-4A, and DPE-6A (all manufactured by Kyoeisha Chemical Co.,Ltd.), KAYARAD PET-30, TMPTA, R-604, DPHA, DPCA-20, -30, -60, and -120,HX-620, D-310, and D-330 (all manufactured by Nippon Kayaku Co., Ltd.),Aronix M208, M210, M215, M220, M240, M305, M309, M310, M315, M325, andM400 (all manufactured by Toagosei Co., Ltd.), and Ripoxy VR-77, VR-60,and VR-90 (all manufactured by Showa Highpolymer Co., Ltd.).

The radical-polymerizable monomers listed above may be used alone or incombination of two or more types thereof.

In the compounds listed above, the (meth)acrylate means the combinationof acrylate and methacrylate sharing common ester moieties. The(meth)acryloyl group means the combination of acryloyl and methacryloylgroups. The term EO refers to ethylene oxide. The EO-modified compoundmeans having a block structure of an ethylene oxide group. The term POrefers to propylene oxide. The PO-modified compound means having a blockstructure of a propylene oxide group.

(1-2) Cation-polymerizable monomer

A compound having one or more vinyl ether groups (CH₂═CH—O—), epoxygroups, or oxetanyl groups can be used as a cation-polymerizablemonomer.

Examples of the compound having one vinyl ether group include, but notlimited to, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether,n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether,n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether,cyclohexylmethyl vinyl ether, 4-methylcyclohexylmethyl vinyl ether,benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethylvinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether,butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether,ethoxyethoxyethyl vinyl ether, methoxy polyethylene glycol vinyl ether,tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether,2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexylmethyl vinyl ether, diethylene glycol monovinyl ether,polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutylvinyl ether, chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, andphenoxy polyethylene glycol vinyl ether.

Examples of the compound having two or more vinyl ether groups include,but not limited to, divinyl ethers such as ethylene glycol divinylether, diethylene glycol divinyl ether, polyethylene glycol divinylether, propylene glycol divinyl ether, butylene glycol divinyl ether,hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, andbisphenol F alkylene oxide divinyl ether; and polyfunctional vinylethers such as trimethylolethane trivinyl ether, trimethylolpropanetrivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinylether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinylether, dipentaerythritol hexavinyl ether, ethylene oxide-addedtrimethylolpropane trivinyl ether, propylene oxide-addedtrimethylolpropane trivinyl ether, ethylene oxide-addedditrimethylolpropane tetravinyl ether, propylene oxide-addedditrimethylolpropane tetravinyl ether, ethylene oxide-addedpentaerythritol tetravinyl ether, propylene oxide-added pentaerythritoltetravinyl ether, ethylene oxide-added dipentaerythritol hexavinylether, and propylene oxide-added dipentaerythritol hexavinyl ether.

Examples of the compound having one epoxy group include, but not limitedto, phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, butylglycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether,1,2-butylene oxide, 1,3-butadiene monooxide, 1,2-epoxydodecane,epichlorohydrin, 1,2-epoxydecane, styrene oxide, cyclohexene oxide,3-methacryloyloxymethyl cyclohexene oxide, 3-acryloyloxymethylcyclohexene oxide, and 3-vinyl cyclohexene oxide.

Examples of the compound having two or more epoxy groups include, butnot limited to, bisphenol A diglycidyl ether, bisphenol F diglycidylether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidylether, brominated bisphenol F diglycidyl ether, brominated bisphenol Sdiglycidyl ether, epoxy novolac resin, hydrogenated bisphenol Adiglycidyl ether, hydrogenated bisphenol F diglycidyl ether,hydrogenated bisphenol S diglycidyl ether,3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate,2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-meta-dioxane, bis(3,4-epoxycyclohexylmethyl) adipate, vinyl cyclohexene oxide, 4-vinylepoxy cyclohexane, bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate,3,4-epoxy-6-methylcyclohexyl-3′, 4′-epoxy-6′-methylcyclohexanecarboxylate, methylenebis(3, 4-epoxycyclohexane), dicyclopentadienediepoxide, di(3, 4-epoxycyclohexylmethyl) ether of ethylene glycol,ethylenebis(3, 4-epoxycyclohexane carboxylate), dioctylepoxyhexahydrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate, 1,4-butanediol diglycidyl ether, 1, 6-hexanediol diglycidyl ether,glycerin triglycidyl ether, trimethylolpropane triglycidyl ether,polyethylene glycol diglycidyl ether, polypropylene glycol diglycidylethers, 1,1,3-tetradecadiene dioxide, limonene dioxide,1,2,7,8-diepoxyoctane, and 1,2,5,6-diepoxycyclooctane.

Examples of the compound having one oxetanyl group include, but notlimited to, 3-ethyl-3-hydroxymethyloxetane,3-(meth)allyloxymethyl-3-ethyloxetane,(3-ethyl-3-oxetanylmethoxy)methylbenzene,4-fluoro-[1-(3-ethyl-3-oxetanylmethoxy)methyl]benzene,4-methoxy-[1-(3-ethyl-3-oxetanylmethoxy)methyl]benzene,[1-(3-ethyl-3-oxetanylmethoxy)ethyl]phenyl ether,isobutoxymethyl(3-ethyl-3-oxetanylmethyl) ether,isobornyloxyethyl(3-ethyl-3-oxetanylmethyl) ether,isobornyl(3-ethyl-3-oxetanylmethyl) ether,2-ethylhexyl(3-ethyl-3-oxetanylmethyl) ether, ethyl diethyleneglycol(3-ethyl-3-oxetanylmethyl) ether,dicyclopentadiene(3-ethyl-3-oxetanylmethyl) ether,dicyclopentenyloxyethyl(3-ethyl-3-oxetanylmethyl) ether,dicyclopentenyl(3-ethyl-3-oxetanylmethyl) ether,tetrahydrofurfuryl(3-ethyl-3-oxetanylmethyl) ether,tetrabromophenyl(3-ethyl-3-oxetanylmethyl) ether,2-tetrabromophenoxyethyl (3-ethyl-3-oxetanylmethyl) ether,tribromophenyl(3-ethyl-3-oxetanylmethyl) ether, 2-tribroinophenoxy ethyl(3-ethyl-3-oxetanylmethyl) ether,2-hydroxyethyl(3-ethyl-3-oxetanylmethyl) ether, 2-hydroxypropyl(3-ethyl-3-oxetanylmethyl) ether, butoxyethyl(3-ethyl-3-oxetanylmethyl)ether, pentachlorophenyl(3-ethyl-3-oxetanylmethyl) ether,pentabromophenyl(3-ethyl-3-oxetanylmethyl) ether, andbornyl(3-ethyl-3-oxetanylmethyl) ether.

Examples of the compound having two or more oxetanyl groups include, butnot limited to, polyfunctional oxetanes such as3,7-bis(3-oxetanyl)-5-oxa-nonane,3,3′-(1,3-(2-methylenyl)propanediylbis(oxymethylene))bis-(3-ethyloxetane),1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene,1,2-bis[(3-ethyl-3-oxetanylmethoxy) methyl]ethane,1,3-bis[(3-ethyl-3-oxetanylmethoxy)methyl]propane, ethylene glycol bis(3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyl bis(3-ethyl-3-oxetanylmethyl) ether, triethylene glycolbis(3-ethyl-3-oxetanylmethyl) ether, tetraethylene glycolbis(3-ethyl-3-oxetanylmethyl) ether,tricyclodecanediyldimethylene(3-ethyl-3-oxetanylmethyl) ether,trimethylolpropane tris(3-ethyl-3-oxetanylmethyl) ether,1,4-bis(3-ethyl-3-oxetanylmethoxy)butane,1,6-bis(3-ethyl-3-oxetanylmethoxy) hexane, pentaerythritoltris(3-ethyl-3-oxetanylmethyl) ether, pentaerythritoltetrakis(3-ethyl-3-oxetanylmethyl) ether, polyethylene glycolbis(3-ethyl-3-oxetanylmethyl) ether, dipentaerythritolhexakis(3-ethyl-3-oxetanylmethyl) ether, dipentaerythritolpentakis(3-ethyl-3-oxetanylmethyl) ether, dipentaerythritoltetrakis(3-ethyl-3-oxetanylmethyl) ether, caprolactone-modifieddipentaerythritol hexakis(3-ethyl-3-oxetanylmethyl) ether,caprolactone-modified dipentaerythritolpentakis(3-ethyl-3-oxetanylmethyl) ether, ditrimethylolpropanetetrakis(3-ethyl-3-oxetanylmethyl) ether, EO-modified bisphenol A bis(3-ethyl-3-oxetanylmethyl) ether, PO-modified bisphenol Abis(3-ethyl-3-oxetanylmethyl) ether, EO-modified hydrogenated bisphenolA bis(3-ethyl-3-oxetanylmethyl) ether, PO-modified hydrogenatedbisphenol A bis(3-ethyl-3-oxetanylmethyl) ether, and EO-modifiedbisphenol F (3-ethyl-3-oxetanylmethyl) ether.

The cation-polymerizable monomers listed above may be used alone or incombination of two or more types thereof. EO refers to ethylene oxide.The EO-modified compound has a block structure of an ethylene oxidegroup. PO refers to propylene oxide. The PO-modified compound has ablock structure of a propylene oxide group.

(2) Photopolymerization initiator (component B)

The photopolymerization initiator (component B) contained in thephotocurable composition of the present invention needs to be selectedappropriately for use according to the properties of the polymerizablemonomer as component A. Specifically, in the case of using theradical-polymerizable monomer as component A, a photo-radical-generatingagent is used. Alternatively, in the case of using thecation-polymerizable monomer as component A, a photo-acid-generatingagent is used.

(2-1) Photo-radical-generating agent

The photo-radical-generating agent refers to a compound that canchemically react upon exposure to radiation such as infrared rays,visible light, ultraviolet rays, far-ultraviolet rays, X-rays, orcharged particle beam (e.g., electron beam) to form a radical necessaryfor the initiation of radical polymerization.

Examples of such compounds include, but not limited to, optionallysubstituted 2,4,5-triarylimidazole dimers such as2-(o-chlorophenyl)-4,5-diphenylimidazole dimer,2-(o-chlorophenyl)-4,5-di(methoxyphenyl)imidazole dimer,2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, and 2-(o- orp-methoxyphenyl)-4,5-diphenylimidazole dimer; benzophenone derivativessuch as benzophenone, N,N′-tetramethyl-4,4′-diaminobenzophenone(Michler's ketone), N,N′-tetraethyl-4,4′-diaminobenzophenone,4-methoxy-4′-dimethylaminobenzophenone, 4-chlorobenzophenone, and4,4′-dimethoxybenzophenone, 4,4′-diaminobenzophenone; aromatic ketonederivatives such as2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propanon-1-one; quinones such as2-ethylanthraquinone, phenanthrenequinone, 2-t-butylanthraquinone,octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone,2-phenylanthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone,2-methylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone,2-methyl-1,4-naphthoquinone, and 2,3-dimethylanthraquinone; benzoinether derivatives such as benzoin methyl ether, benzoin ethyl ether, andbenzoin phenyl ether; benzoin derivatives such as benzoin,methylbenzoin, ethylbenzoin, and propylbenzoin; benzyl derivatives suchas benzyldimethylketal; acridine derivatives such as 9-phenyl acridineand 1,7-bis(9,9′-acridinyl)heptane; N-phenylglycine derivatives such asN-phenylglycine; acetophenone derivatives such as acetophenone,3-methylacetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexylphenyl ketone, and 2,2-dimethoxy-2-phenylacetophenone; thioxanthonederivatives such as thioxanthone, diethylthioxanthone,2-isopropylthioxanthone, 2-chlorothioxanthone; and xanthone, fluorenone,benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole,1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one,2-hydroxy-2-methyl-1-phenylpropan-1-one,2,4,6-trimethylbenzoyldiphenylphosphine oxide, andbis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide.

Of the compounds described above, examples of the commercially availablephoto-radical-generating agent include, but not limited to, Irgacure184, 369, 651, 500, 819, 907, 784, and 2959, CGI-1700, -1750, and -1850,CG24-61, and Darocur 1116 and 1173 (all manufactured by Ciba Japan Co.,Ltd.), Lucirin TPO, LR8893, and LR8970 (all manufactured by BASF), andUbecryl P36 (manufactured by UCB).

The photo-radical-generating agents listed above may be used alone or incombination of two or more types thereof.

(2-2) Photo-acid-Generating Agent

The photo-acid-generating agent refers to a compound that can chemicallyreact upon exposure to radiation such as infrared rays, visible light,ultraviolet rays, far-ultraviolet rays, X-rays, or charged particle beam(e.g., electron beam) to form an acid (proton) for the initiation ofcation polymerization. Examples of such compounds include, but notlimited to, onium salt compounds, sulfone compounds, sulfonic acid estercompounds, sulfonimide compounds, and diazomethane compounds. In thepresent invention, an onium salt compound is preferably used.

Examples of the onium salt compound can include iodonium salt, sulfoniumsalt, phosphonium salt, diazonium salt, ammonium salt, and pyridiniumsalt. Specific examples of the onium salt compound include, but notlimited to, bis(4-t-butylphenyl)iodonium perfluoro-n-butanesulfonate,bis(4-t-butylphenyl) iodonium trifluoromethanesulfonate,bis(4-t-butylphenyl)iodonium 2-trifluoromethylbenzenesulfonate,bis(4-t-butylphenyl) iodonium pyrenesulfonate, bis(4-t-butylphenyl)iodonium n-dodecylbenzenesulfonate, bis(4-t-butylphenyl)iodoniump-toluenesulfonate, bis(4-t-butylphenyl) iodonium benzenesulfonate, bis(4-t-butylphenyl) iodonium 10-camphorsulfonate, bis(4-t-butylphenyl)iodonium n-octanesulfonate, diphenyliodoniumperfluoro-n-butanesulfonate, diphenyliodonium trifluoromethanesulfonate,diphenyliodonium 2-trifluoromethylbenzenesulfonate, diphenyliodoniumpyrenesulfonate, diphenyliodonium n-dodecylbenzenesulfonate,diphenyliodonium p-toluenesulfonate, diphenyliodonium benzenesulfonate,diphenyliodonium 10-camphorsulfonate, diphenyliodoniumn-octanesulfonate, triphenylsulfonium perfluoro-n-butanesulfonate,triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium2-trifluoromethylbenzenesulfonate, triphenylsulfonium pyrenesulfonate,triphenylsulfonium n-dodecylbenzenesulfonate, triphenylsulfoniump-toluenesulfonate, triphenylsulfonium benzenesulfonate,triphenylsulfonium 10-camphorsulfonate, triphenylsulfoniumn-octanesulfonate, diphenyl(4-t-butylphenyl) sulfoniumperfluoro-n-butanesulfonate, diphenyl(4-t-butylphenyl)sulfoniumtrifluoromethanesulfonate, diphenyl(4-t-butylphenyl) sulfonium2-trifluoromethylbenzenesulfonate, diphenyl(4-t-butylphenyl)sulfoniumpyrenesulfonate, diphenyl(4-t-butylphenyl)sulfoniumn-dodecylbenzenesulfonate, diphenyl(4-t-butylphenyl) sulfoniump-toluenesulfonate, diphenyl(4-t-butylphenyl) sulfoniumbenzenesulfonate, diphenyl(4-t-butylphenyl)sulfonium10-camphorsulfonate, diphenyl(4-t-butylphenyl)sulfoniumn-octanesulfonate, tris (4-methoxyphenyl)sulfoniumperfluoro-n-butanesulfonate, tris(4-methoxyphenyl)sulfoniumtrifluoromethanesulfonate, tris(4-methoxyphenyl)sulfonium2-trifluoromethylbenzenesulfonate, tris(4-methoxyphenyl)sulfoniumpyrenesulfonate, tris (4-methoxyphenyl)sulfoniumn-dodecylbenzenesulfonate, tris(4-methoxyphenyl)sulfoniump-toluenesulfonate, tris(4-methoxyphenyl)sulfonium benzenesulfonate,tris(4-methoxyphenyl)sulfonium 10-camphorsulfonate, andtris(4-methoxyphenyl)sulfonium n-octanesulfonate.

Examples of the sulfone compound can include β-ketosulfone,β-sulfonylsulfone, and α-diazo compounds thereof. Specific examples ofthe sulfone compound include, but not limited to, phenacyl phenylsulfone, mesityl phenacyl sulfone, bis(phenylsulfonyl)methane, and4-trisphenacylsulfone.

Examples of the sulfonic acid ester compound can include alkylsulfonicacid ester, haloalkylsulfonic acid ester, arylsulfonic acid ester, andiminosulfonate. Specific examples of the sulfonic acid ester compoundinclude, but not limited to, α-methylolbenzoinperfluoro-n-butanesulfonate, α-methylolbenzointrifluoromethanesulfonate, and α-methylolbenzoin2-trifluoromethylbenzenesulfonate.

Specific examples of the sulfonimide compound include, but not limitedto, N-(trifluoromethylsulfonyloxy)succinimide,N-(trifluoromethylsulfonyloxy) phthalimide,N-(trifluoromethylsulfonyloxy)diphenylmaleimide,N-(trifluoromethylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide,N-(trifluoromethylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboximide,N-(trifluoromethylsulfonyloxy)bicyclo[2.2.1]heptane-5,6-oxy-2,3-dicarboximide,N-(trifluoromethylsulfonyloxy)naphthylimide,N-(10-camphorsulfonyloxy)succinimide,N-(10-camphorsulfonyloxy)phthalimide,N-(10-camphorsulfonyloxy)diphenylmaleimide,N-(10-camphorsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2, 3-dicarboximide,N-(10-camphorsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboximide,N-(10-camphorsulfonyloxy) bicyclo[2.2.1]heptane-5,6-oxy-2,3-dicarboximide, N-(10-camphorsulfonyloxy)naphthylimide,N-(4-methylphenylsulfonyloxy)succinimide,N-(4-methylphenylsulfonyloxy)phthalimide,N-(4-methylphenylsulfonyloxy)diphenylmaleimide,N-(4-methylphenylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide,N-(4-methylphenylsulfonyloxy)-7-oxabicyclo[2.2.l]hept-5-ene-2,3-dicarboximide,N-(4-methylphenylsulfonyloxy)bicyclo[2.2.1]heptane-5,6-oxy-2,3-dicarboximide,N-(4-methylphenylsulfonyloxy)naphthylimide,N-(2-trifluoromethylphenylsulfonyloxy)succinimide,N-(2-trifluoromethylphenylsulfonyloxy)phthalimide,N-(2-trifluoromethylphenylsulfonyloxy)diphenylmaleimide,N-(2-trifluoromethylphenylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide,N-(2-trifluoromethylphenylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboximide,N-(2-trifluoromethylphenylsulfonyloxy)bicyclo[2.2.1]heptane-5,6-oxy-2,3-dicarboximide,N-(2-trifluoromethylphenylsulfonyloxy)naphthylimide,N-(4-fluorophenylsulfonyloxy)succinimide, N-(4-fluorophenyl)phthalimide,N-(4-fluorophenylsulfonyloxy)diphenylmaleimide,N-(4-fluorophenylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide,N-(4-fluorophenylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboximide,N-(4-fluorophenylsulfonyloxy)bicyclo[2.2.1]heptane-5,6-oxy-2,3-dicarboximide,and N-(4-fluorophenylsulfonyloxy)naphthylimide.

Specific examples of the diazomethane compound include, but not limitedto,

bis(trifluoromethylsulfonyl)diazomethane,

bis(cyclohexylsulfonyl)diazomethane,

bis(phenylsulfonyl)diazomethane, bis(p-toluenesulfonyl) diazomethane,methylsulfonyl p-toluenesulfonyldiazomethane,(cyclohexylsulfonyl)(1,1-dimethylethylsulfonyl)diazomethane, andbis(1,1-dimethylethylsulfonyl) diazomethane.

Of these photo-acid-generating agents, an onium salt compound ispreferred. In the present invention, the photo-acid-generating agentslisted above may be used alone or in combination of two or more typesthereof.

The blending ratio of the photopolymerization initiator (B) component is0.01% by weight or more and 10% by weight or less, preferably 0.1% byweight or more and 7% by weight or less, with respect to the totalamount of the polymerizable monomer (component A) contained in thephotopolymerization composition of the present invention. If theblending ratio is less than 0.01% by weight, the resulting photocurablecomposition may have low reaction efficiency due to a reduced curingrate. If the blending ratio exceeds 10% by weight, a cured product ofthe resulting photocurable composition for photo-imprint may be inferiorin mechanical properties.

(3) Fluorine atom-containing surfactant (component C) It is desired thatthe photocurable composition of the present invention should contain afluorine atom-containing surfactant. The fluorine atom-containingsurfactant is distributed in a thin film form in the interface between aphotocured product and a mold during photocured product preparationdescribed later. The fluorine atom-containing surfactant serves as akind of coating material for a photocured product. In this context, thefluorine atom contained in the fluorine atom-containing surfactantbrings about the effect of reducing surface energy. It is consideredthat mold release force required for demolding a mold from thephotocured product in photocured product preparation can be reduced byvirtue of this effect.

The fluorine atom-containing surfactant contained in the photocurablecomposition of the present invention is preferably a compound havingethylene oxide (—CH₂CH₂O—), more preferably a compound represented bythe following formula [1]:

R₁ —x ₁—R₂ —x ₂—R₃  [1],

In the formula [1], R₁ represents a perfluoroalkyl group. Specificexamples of the perfluoroalkyl group represented by R₁ include linearalkyl groups having 2 to 20 carbon atoms and fluorine atoms replaced forall hydrogen atoms, such as perfluoroethyl, perfluoropropyl,perfluorobutyl, perfluoropentyl, perfluorohexyl, perfluoroheptyl,perfluorooctyl, perfluorononyl, and perfluorodecyl groups. The number ofcarbon atoms in the perfluoroalkyl group can be 7 or less from theviewpoint of environment safety.

In the formula [1], R₂ represents a divalent substituent containingethylene oxide. In this context, the divalent substituent containingethylene oxide is specifically the following divalent substituent (i) or(ii):

(i) a polyalkylene oxide chain containing ethylene oxide; and

(ii) an alkyl chain containing ethylene oxide.

Specific examples of the divalent substituent (i) include polyethyleneoxide chains having 1 to 100 repeating units and polypropylene oxidechains (—CH₂CH (CH₃)O—) having 1 to 100 repeating units.

Specific examples of the divalent substituent (ii) include a polymerchain having a polyethylene oxide chain having 1 to 100 repeating unitsand a linear alkyl group having 2 to 100 carbon atoms, and a polymerchain having a polyethylene oxide chain having 1 to 100 repeating unitsand an alkyl group containing a cyclic structure.

In the formula [1], R₃ represents a polar functional group. Examples ofthe polar functional group represented by R₃ include alkylhydroxyl,carboxyl, thiol, pyridyl, silanol, and sulfo groups.

In the formula [1], x₁ and x₂ each represent a single bond or a divalentsubstituent. In the case where either x₁ or x₂ is a divalentsubstituent, specific examples thereof include alkylene, phenylene,naphthylene, ester, ether, thioether, sulfonyl, secondary amino,tertiary amino, amide, and urethane groups.

These fluorine atom-containing surfactants may be used alone or incombination of two or more types thereof.

The blending ratio of the fluorine atom-containing surfactant containedin the photocurable composition of the present invention is determinedwith respect to the total amount of the polymerizable monomer (componentA) contained in the photocurable composition.

Specifically, the blending ratio is 0.001% by weight to 5% by weight,preferably 0.002% by weight to 4% by weight, more preferably 0.005% byweight to 3% by weight, of the total amount of component A.

Additional Component

The photocurable composition of the present invention may containadditional components according to various purposes without impairingthe effects of the present invention, in addition to the polymerizablemonomer (component A), photopolymerization initiator (component B), andfluorine atom-containing surfactant (component C) described above. Inthis context, the additional components are specifically components suchas sensitizers, antioxidants, solvents, and polymer components.Hereinafter, their respective specific examples will be described.

Sensitizer

The photocurable composition of the present invention may besupplemented with a sensitizer for the purpose of promotingpolymerization reaction or improving the rate of conversion of thereaction. A hydrogen donor or a sensitizing dye may be added thereto asthe sensitizer.

The hydrogen donor refers to a compound that reacts with an initiatingradical formed from the photopolymerization initiator (component B) or aradical at the propagating end to form a more highly reactive radical.The hydrogen donor can be added in the case where thephotopolymerization initiator (component B) is aphoto-radical-generating agent.

A heretofore known compound commonly used can be used as the hydrogendonor. Specifically, examples thereof include, but not limited to, aminecompounds such as N-butylamine, di-n-butylamine, tri-n-butylphosphine,allylthiourea, s-benzylisothiuronium-p-toluenesulfinate, triethylamine,diethylaminoethyl methacrylate, triethylenetetramine,4,4′-bis(dialkylamino)benzophenone, N,N-dimethylaminobenzoic acid ethylester, N,N-dimethylaminobenzoic acid isoamyl ester,pentyl-4-dimethylaminobenzoate, triethanolamine, and N-phenylglycine;and mercapto compounds such as 2-mercapto-N-phenylbenzimidazole andmercaptopropionic acid ester.

The sensitizing dye refers to a compound having the property of beingexcited by the absorption of light having a particular wavelength toinduce interaction with the photopolymerization initiator (component B).In this context, the interaction specifically encompasses energytransfer, electron transfer, or the like from the sensitizing dye in anexcited state.

A heretofore known compound commonly used can be used as the sensitizingdye. Specifically, examples thereof include, but not limited to,anthracene derivatives, anthraquinone derivatives, pyrene derivatives,perylene derivatives, carbazole derivatives, benzophenone derivatives,thioxanthone derivatives, xanthone derivatives, thioxanthonederivatives, coumarin derivatives, phenothiazine derivatives,camphorquinone derivatives, acridine dyes, thiopyrylium salt dyes,merocyanine dyes, quinoline dyes, styrylquinoline dyes, ketocoumarindyes, thioxanthene dyes, xanthene dyes, oxonol dyes, cyanine dyes,rhodamine dyes, and pyrylium salt dyes.

These sensitizers may be used alone or in combination of two or moretypes thereof. The content of the sensitizer in the photocurablecomposition of the present invention is preferably 0 to 20% by weight,more preferably 0.1% by weight to 5.0% by weight, further preferably0.2% by weight to 2.0% by weight, with respect to the total amount ofthe polymerizable monomer as component A. In this context, thesensitizer at a content of 0.1% by weight or more can more effectivelyexert its effects. Also, the sensitizer at a content of 5% by weight orless results in a photocured product that has a sufficiently highmolecular weight and can be prevented from causing poor dissolution ordeterioration of storage stability.

Method for Blending Each Component

The photocurable composition of the present invention can be prepared bymixing the components described above. In this context, temperatureconditions for mixing and dissolving the components of the photocurablecomposition usually range from 0° C. to 100° C. A solvent may be usedfor preparing the photocurable composition. In this context, the solventused for preparing the photocurable composition is not particularlylimited as long as the solvent does not cause phase separation from thepolymerizable monomer.

Viscosity of Composition

The viscosity of the photocurable composition of the present inventionis preferably 1 cP to 100 cP, more preferably 5 cP to 50 cP, furtherpreferably 6 cP to 20 cP, in terms of the viscosity of the mixture ofthe components except for the solvent at 23° C. A photocurablecomposition having viscosity higher than 100 cP may require a long timefor filling depressed portions in the fine pattern on a mold with thecomposition when contacted with the mold or may cause pattern defectsdue to poor filling. By contrast, a photocurable composition havingviscosity lower than 1 cP may be unevenly spread during coating or maybe leaked from the end of a mold when contacted with the mold.

Surface Tension of Composition

The surface tension of the photocurable composition of the presentinvention is preferably 5 mN/m to 70 mN/m, more preferably 7 mN/m to 35mN/m, further preferably 10 mN/m to 32 mN/m, in terms of the surfacetension of the mixture of the components except for the solvent at 23°C. In this context, a photocurable composition having surface tensionlower than 5 mN/m requires a long time for filling depressed portions inthe fine pattern on a mold with the composition when contacted with themold. By contrast, a photocurable composition having surface tensionhigher than 70 mN/m has low surface smoothness.

Impurities

It is desired that impurities should be removed as much as possible fromthe photocurable composition of the present invention. For example, thecomponents of the photocurable composition can be mixed and thenfiltered through, for example, a filter having a pore size of 0.001 μmto 5.0 μm in order to prevent particles contaminating the photocurablecomposition from causing pattern defects in a photocured product. Thefiltration using a filter can be carried out at multiple stages orrepeated several times.

Alternatively, the filtrate may be filtered again. A filter made ofpolyethylene resin, polypropylene resin, fluorine resin, nylon resin, orthe like can be used in the filtration, though the filter is not limitedthereto.

In the case of using the photocurable composition of the presentinvention for producing a semiconductor integrated circuit, thecontamination of the composition with metal impurities can be minimizedso as not to inhibit the operation of the product. In this regard, theconcentration of metal impurities contained in the photocurablecomposition of the present invention is preferably 10 ppm or lower, morepreferably 100 ppb or lower.

Method for producing photocured product Next, the method for producingthe photocured product will be described.

FIGS. 1A to 1F are each a cross-sectional view schematicallyillustrating one example of a production process of the method forproducing the photocured product of the present invention. Thephotocured product of the present invention is produced according to theproduction process illustrated in FIGS. 1A to 1F, i.e., steps (i) to (v)shown below. The method of the present invention includes at least steps(i) to (iv) shown below. For the actual production of the photocuredproduct, the step of preparing a photocurable composition containing apolymerizable monomer and a fluorine atom-containing surfactant(photocurable composition preparation step) is performed before step (i)(coating film formation step):

(i) the step of coating a substrate with a photocurable composition toform a coating film (coating film formation step; FIG. 1A);

(ii) the step of contacting the coating film with a mold (imprintingstep; FIGS. 1B and 1C);

(iii) the step of irradiating the coating film with light via the moldto cure the coating film (light irradiation step; FIG. 1D);

(iv) the step of releasing the mold from the coating film thusirradiated with light to form a film having a predetermined patternshape on the substrate (mold release step; FIG. 1E); and

(v) the step of removing a residual film that remains in a region fromwhich the coating film should be removed in the pattern shape (residualfilm removal step; FIG. 1F).

Hereinafter, the steps (i) to (v) will be described in detail. Themethod for producing the photocured product of the present invention isa nanoimprint method using light. Also, the film produced by theproduction method of the present invention has a pattern of preferably 1nm to 10 mm, more preferably approximately 10 nm to 100 μm, in size.

(1) Coating Film Formation Step

First, the step of coating a substrate with a photocurable compositionto form a coating film (coating film formation step) is performed. Inthis step (coating film formation step), as illustrated in FIG. 1A, acoating film made of a photocurable composition, i.e.,pattern-replicating layer 1, is formed on a substrate material(substrate 2).

A silicon wafer is usually used as the substrate material, though thesubstrate material is not limited thereto. Instead of the silicon wafer,the substrate material can be selected arbitrarily for use from amongknown substrates for semiconductor devices made of aluminum,titanium-tungsten alloy, aluminum-silicon alloy, aluminum-copper-siliconalloy, silicon oxide, silicon nitride, or the like. The substrate(substrate material) used may be surface-treated by, for example, silanecoupling treatment, silazane treatment, or thin organic film formation,thereby improving the adhesion of the substrate to the photocurablecomposition.

For example, an ink jet, dip coat, air knife coat, curtain coat, wirebar coat, gravure coat, extrusion coat, spin coat, or slit scan methodcan be used for coating the substrate material with the photocurablecomposition of the present invention. The film thickness of thepattern-replicating layer (coating film) differs depending on how to usethe product and is, for example, 0.01 μm to 100.0 μm.

(2) Imprinting Step

Next, the step of contacting the coating film formed in the precedingstep (coating film formation step) with a mold (imprinting step; FIGS.1B and 1C) is performed. In this step (imprinting step), a mold 3 iscontacted with the pattern-replicating layer 1 (FIG.1B) so thatdepressed portions in the fine pattern formed on the mold 3 are filledwith (a portion of) the coating film 10 (FIG. 1C).

The mold 3 used in the contact step needs to be made of alight-transmissive material in consideration of the subsequent step(light irradiation step). Examples of the constituent material for themold can specifically include glass, quartz, light-transparent resinssuch as PMMA and polycarbonate resins, transparent vapor-deposited metalfilms, flexible films such as polydimethylsiloxane, photo-curable films,and metal films. In the case of using a light-transparent resin as theconstituent material for the mold, it is required to select a resin thatis not soluble in the solvent contained in the photocurable composition1.

The mold 3 used in the method for producing the photocured product ofthe present invention may be surface-treated in order to improve thedemolding between the photocurable composition 1 and the surface of themold 3. The surface treatment method may be treatment with a silicone orfluorine silane coupling agent or may specifically use a commerciallyavailable coating-type mold release agent such as Optool DSXmanufactured by Daikin Industries, Ltd.

In the contact step, as illustrated in FIG. 1B, the pressure applied tothe pattern-replicating layer 1 when the mold 3 is contacted with thepattern-replicating layer 1 is not particularly limited and is usually0.1 MPa to 100 MPa. Particularly, 0.1 MPa to 50 MPa is preferred, and0.1 MPa to 30 MPa is more preferred, with 0.1 MPa to 20 MPa furtherpreferred. Also, in the contact step, the duration of the contactbetween the mold 3 and the pattern-replicating layer 1 is notparticularly limited and is usually 1 second to 600 seconds, preferably1 second to 300 seconds, more preferably 1 second to 180 seconds,particularly preferably 1 second to 120 seconds.

The contact step can be performed under any condition selected from anambient atmosphere, a reduced-pressure atmosphere, and an inert gasatmosphere. In the case of performing the imprinting step in an inertgas atmosphere, specific examples of the inert gas used includenitrogen, carbon dioxide, helium, argon, various chlorofluorocarbongases, and mixed gases thereof.

(3) Light Irradiation Step

Next, the step of irradiating the coating film with light via the mold(light irradiation step; FIG. 1C) is performed. In this step, thecoating film is cured by light irradiation to form a photocured product11.

In this context, the light with which the pattern-replicating layer 1 isirradiated is selected according to the sensitivity wavelength of thephotocurable composition and can specifically be selected appropriatelyfor use from among ultraviolet light, X-rays, electron beam, and thelike having a wavelength on the order of 150 nm to 400 nm. In thiscontext, many commercially available photopolymerization initiators(component B) are compounds having sensitivity to ultraviolet light. Forthis reason, the light with which the pattern-replicating layer 1 isirradiated (irradiation light 4) is particularly preferably ultravioletlight. In this context, examples of the light source of the ultravioletlight include high-pressure mercury lamps, ultrahigh-pressure mercurylamps, low-pressure mercury lamps, Deep-UV lamps, carbon-arc lamps,chemical lamps, metal halide lamps, xenon lamps, KrF excimer laser, ArFexcimer laser, and F₂ excimer laser. An ultrahigh-pressure mercury lampis particularly preferred. The number of the light sources used may beone or may be two or more. The light irradiation may be performed forthe whole surface of the pattern-replicating layer 1 or may be performedonly for a partial region thereof.

Alternatively, the pattern-replicating layer may be cured thermally. Insuch a case, heat curing may be further performed. In the case of heatcuring, the atmosphere and temperature, etc. of heating are notparticularly limited. For example, the pattern-replicating layer 1 canbe heated at a temperature ranging from 40° C. to 200° C. in an inertatmosphere or under reduced pressure. Also, the pattern-replicatinglayer 1 can be heated using a hot plate, an oven, a furnace, or thelike.

(4) Mold Release Step

Next, the step of releasing the mold from the photocurable compositionto form a film having a predetermined pattern shape on the substrate(mold release step; FIG. 1E). This step (mold release step) is the stepof demolding the mold from the pattern-replicating layer, whereby areversed pattern of the fine pattern formed on the mold is obtained as apattern in the photocurable composition cured in the preceding step(light irradiation step).

The method for demolding the mold 3 from the cured pattern-replicatinglayer (cured film 11) is not particularly limited as long as thedemolding method does not physically damage a portion of the cured film11. Likewise, various conditions, etc. are not particularly limited. Forexample, the substrate material (substrate 2) is fixed, and the mold 3may be moved away from the substrate material, thereby demolding themold. Alternatively, the mold 3 is fixed, and the substrate material maybe moved away from the mold, thereby demolding the mold. Alternatively,the mold 3 and the substrate material may be pulled toward oppositedirection, thereby demolding the mold.

Also, the mold 3 may be demolded from the cured film 11 by adopting amethod using a coating-type mold release agent. In this context, fordemolding the mold 3 from the cured film 11 using the coating-type moldrelease agent, the step of forming a coating-type mold release agentlayer on the surface of the mold having the desired pattern is performedbefore the imprinting step.

Examples of the type of the coating-type mold release agent usedinclude, but not particularly limited to, silicon mold release agents,fluorine mold release agents, polyethylene mold release agents,polypropylene mold release agents, paraffin mold release agents, montanwax mold release agents, and carnauba wax mold release agents. Thesemold release agents may be used alone or in combination of two or moretypes thereof. Among these mold release agents, a fluorine mold releaseagent is particularly preferred.

(5) Residual Film Removal Step

The film obtained by the mold release step has a particular patternshape. However, a portion of the film may exist as a residual film in aregion other than the region having this pattern shape. Thus, the stepof removing a photocurable composition (residual film) that remains in aregion from which the photocurable composition should be removed in thepattern shape (residual film removal step; FIG. 1F) is performed.

In this context, examples of the method for removing the residual filminclude a method involving removing the film (residual film) thatremains in the depressed portions of the pattern-replicating layer byetching to expose the surface of the substrate material at the depressedportions in the pattern.

A specific method for the etching used is not particularly limited, anda heretofore known method, for example, dry etching can be performed. Aheretofore known dry etching apparatus can be used in the dry etching. Asource gas for the dry etching is selected appropriately according tothe element composition of the film to be etched. For example, oxygenatom-containing gas such as O₂, CO, or CO₂, inert gas such as He, N₂, orAr, chlorine gas such as Cl₂ or BCl₃, or any of other gases such as H₂or NH₃ can be used. These gases may be mixed for use.

The film having the pattern formed by the photo-nanoimprint method asdescribed above can be used as, for example, a film for interlayerinsulators for semiconductor devices such as LSI, system LSI, DRAM,SDRAM, RDRAM, or D-RDRAM or a resist film for semiconductor deviceproduction.

Specifically, the present invention provides methods according to thefollowing embodiments using the photocurable composition of theembodiment described above.

The present invention provides a method for forming a pattern in a curedproduct using a mold having a elevated/depressed surface and a methodfor producing a cured product having a pattern.

The present invention also provides, as a method for producing a circuitsubstrate such as a semiconductor device, a method for producing acircuit substrate, comprising; applying a photocurable composition ontoa substrate material/ ppressing a mold against the photocurablecomposition to form a pattern in the photocurable composition;irradiating the photocurable composition having the pattern with lightto prepare a cured product having the pattern; and releasing the moldfrom the curied product to form, on the substrate material, a circuitstructure based on the pattern in the cured product.

EXAMPLES

Hereinafter, the present invention will be described in more detail withreference to Examples. However, the present invention is not limited toExamples described below. In the description below, the term “part”means “part by weight” unless otherwise specified. The term “%” means “%by weight” unless otherwise specified.

Synthesis Example 1 Synthesis of Fluorine Atom-containing Surfactant(C-1)

(1) The inside of a 300-mL reactor was kept in a nitrogen atmosphere,while the following reagents and solvents were added into this reactor:

Hexaethylene glycol (PEG6): 26.5 g (93.9 mmol, 1.0 eq.)

Carbon tetrachloride (CCl₄): 36.1 g (235 mmol, 2.5 eq.)

Tetrahydrofuran (THF): 106 mL

Next, the reaction solution was cooled to −30° C. Next,dimethylaminophosphine (15.3 g, 93.9 mmol, 1.0 eq.) diluted in THF (24mL) was gradually added to the reaction solution over 2 hours, and themixture was then stirred at the same temperature for 30 minutes. Next,the reactor was taken out of the cooling bath, and the reaction solutionwas then stirred at room temperature for 2 hours. Subsequently, citywater (250 mL) was added to the reaction solution (pale yellowsuspension) to separate the reaction solution into two layers (CCl₄layer and aqueous layer). Then, the aqueous layer was collected.Subsequently, the aqueous layer was washed twice with isopropyl ether(IPE) (150 mL). Next, a suspension obtained by suspending potassiumhexafluorophosphate (KPF_(6,)34.5 g, 188 mmol, 2.0 eq.) in city water(250 mL) was prepared and then added to the aqueous layer, and themixture was then sufficiently stirred. Subsequently, solvent extractionoperation was performed three times using dichloromethane (200 mL) . Theorganic layers were combined, then washed with city water (400 mL) andsaturated saline (300 mL) in this order, and dried over anhydrousmagnesium sulfate. Then, the organic layer was concentrated underreduced pressure to obtain 53 g of a light brown liquid (hereinafter,referred to as component “C-1-a”).

(2) The Following Reagents and Solvents were Added to a 500-mL Reactor

1H, 1H-perfluoro-1-heptanol: 34.2 g (97.7 mmol, 1.2 eq.) THF: 120 mL

Next, 60% NaH (3.9 g, 97.7 mmol, 1.2 eq.) was gradually added to thereaction solution without foaming the reaction solution. Then, thereaction solution was heated to 50° C. and stirred at this temperature(50° C.) for 1 hour. Subsequently, the solvent was distilled off underreduced pressure. To the obtained residue, component C-1-a (53 g)dissolved in anhydrous dioxane (600 mL) was added. Subsequently, thereaction solution was heated to 60° C. and stirred at this temperature(60° C.) for 48 hours. Subsequently, the reaction solution in asuspension state was concentrated under reduced pressure. To theobtained residue, city water (300 mL) and ethyl acetate (300 mL) wereadded, and an organic layer was collected by solvent extractionoperation. Subsequently, the aqueous layer was subjected to solventextraction operation with ethyl acetate (200 mL) twice, and the obtainedorganic layer was combined with the preliminarily collected organiclayer. Subsequently, this organic layer was washed with city water (400mL) and saturated saline (400 mL) in this order and then dried overanhydrous magnesium sulfate. Subsequently, the organic layer wasconcentrated under reduced pressure to obtain 59.1 g of a brown liquid.The obtained brown liquid was purified by column chromatography (packingmaterial: SiO₂ (1.2 kg), developing solvent: only ethyl acetate→ethylacetate/methanol=10/1). Next, the purified product was further purifiedby column chromatography (packing material: SiO₂ (400 g), developingsolvent: chloroform/methanol=15/1→10/1). Subsequently, the purifiedproduct was dried under high vacuum. In this way, 19.2 g (31.2 mmol,yield: 33%) of the fluorine atom-containing surfactant F (CF₂)₆CH₂(OCH₂CH₂)₆OH serving as component C-1 was obtained as a colorlessliquid.

Synthesis Example 2 Synthesis of Fluorine Atom-containing Surfactant(C-2)

(1) The inside of a 100-mL reactor was kept in a nitrogen atmosphere,while the following reagents and solvents were added into this reactor:

Hexapropylene glycol (P400): 20 g (50 mmol, 1.0 eq.)

Carbon tetrachloride (CCl₄): 19.2 g (125 mmol, 2.5 eq.)

Tetrahydrofuran (THF): 100 mL)

Next, the reaction solution was cooled to −30° C. Next,dimethylaminophosphine (8.16 g, 10 mmol, 1.0 eq.) diluted in THF (30 mL)was gradually added to the reaction solution over 2 hours, and themixture was then stirred at the same temperature for 30 minutes. Next,the reactor was taken out of the cooling bath, and the reaction solutionwas then stirred at room temperature for 2 hours. Subsequently, citywater (350 mL) was added to the reaction solution (pale yellowsuspension) to separate the reaction solution into two layers (CCl₄layer and aqueous layer). Then, the aqueous layer was collected.Subsequently, the aqueous layer was washed twice with isopropyl ether(IPE) (150 mL). Next, a suspension obtained by suspending potassiumhexafluorophosphate (18.4 g, 100 mmol, 2.0 eq.) in city water (250 mL)was prepared and then added to the aqueous layer, and the mixture wasthen sufficiently stirred. Subsequently, solvent extraction operationwas performed three times using dichloromethane (150 mL). The organiclayers were combined, then washed with city water (500 mL) and saturatedsaline (300 mL) in this order, and dried over anhydrous magnesiumsulfate. Then, the organic layer was concentrated under reduced pressureto obtain 31 g of a light brown liquid (hereinafter, referred to ascomponent “C-2-a”).

(2) The following reagents and solvents were added to a 500-mL reactor:

1H, 1Hperfluoro-1-heptanol: 21 g (60 mmol, 1.2 eq.) THF: 120 mL)

Next, 60% NaH (3.9 g, 97.7 mmol, 1.2 eq.) was gradually added to thereaction solution without foaming the reaction solution. Then, thereaction solution was heated to 40° C. and stirred at this temperature(40° C.) for 1 hour. Subsequently, the solvent was distilled off underreduced pressure. To the obtained residue, component C-2-a (31 g)dissolved in anhydrous dioxane (350 mL) was added. Subsequently, thereaction solution was heated to 60° C. and stirred at this temperature(60° C.) for 24 hours. Subsequently, the reaction solution in asuspension state was concentrated under reduced pressure. To theobtained residue, city water (200 mL) and ethyl acetate (200 mL) wereadded, and an organic layer was collected by solvent extractionoperation. Subsequently, the aqueous layer was subjected to solventextraction operation with ethyl acetate (150 mL) twice, and the obtainedorganic layer was combined with the preliminarily collected organiclayer. Subsequently, this organic layer was washed with city water (500mL) and saturated saline (500 mL) in this order and then dried overanhydrous magnesium sulfate. Subsequently, the organic layer wasconcentrated under reduced pressure to obtain 29 g of a brown liquid.The obtained brown liquid was purified by column chromatography (packingmaterial: SiO₂ (0.9 kg), developing solvent: ethylacetate/hexane=2/1→only ethyl acetate). Next, the purified product wasfurther purified by column chromatography (packing material: SiO2 (300g), developing solvent: chloroform/methanol=20/1→10/1). Subsequently,the purified product was dried under high vacuum. In this way, 1.71 g(2.78 mmol, yield: 14%) of the fluorine atom-containing surfactant F(CF₂)₆CH₂(OCH₂C₂H₄)₆OH serving as component C-2 was obtained as acolorless liquid.

Example 1

(1) Preparation of Photocurable Composition

First, the following reagents and solvents were mixed:

(component A) isobornyl acrylate (manufactured by Kyoeisha Chemical Co.,Ltd.): 62 parts by weight

(component A) 1,6-hexanediol diacrylate (manufactured by Osaka OrganicChemical Industry, Ltd.): 22 parts by weight

(component A) Medol 10 (manufactured by Osaka Organic Chemical Industry,Ltd.): 16 parts by weight

(component B) Irgacure 369 (manufactured by Ciba Japan Co., Ltd.): 3parts by weight

(component C-1) fluorine atom-containing surfactant(F(CF₂)₆CH₂(OCH₂CH₂)₆OH):2 parts by weight

Next, a mixed solution of components A, B and C-1 was filtered through a0.2 μm filter made of tetrafluoroethylene to obtain photocurablecomposition (a-1) of this Example (Example 1).

The surface tension of the obtained photocurable composition wasmeasured using an automatic surface tensiometer CBVP-A3 (manufactured byKyowa Interface Science Co., Ltd.) and consequently determined to be23.9 mN/m. Also, the viscosity of the obtained photocurable compositionwas measured using a rotary cone-plate viscometer RE-85L (manufacturedby Toki Sangyo Co., Ltd.) and consequently determined to be 6.95 CP.

(2) Preparation of Photocured Product

(2-1) Film Formation Step

15 μl of the photocurable composition (a-1) was added dropwise onto a4-inch silicon wafer using a micropipette to form a film. In thiscontext, an adhesion-promoting layer serving as an adhesive layer wasformed at a thickness of 60 nm on this silicon wafer.

(2-2) Contact Step

Next, a 40 mm×40 mm quartz mold neither surface-treated nor patternedwas placed on the silicon wafer and contacted with the photocurablecomposition (a-1).

(2-3) Light Irradiation Step

Next, the photocurable composition (a-1) in contact with the quartz moldwas irradiated with light for 60 seconds. This light irradiation used aUV light source EXECURE 3000 (manufactured by Hoya Candeo OptronicsCorporation) equipped with a 200 W mercury xenon lamp as an irradiationlight source. Also, an interference filter VPF-50C-10-25-36500(manufactured by Sigma Koki Co., Ltd.) was disposed between theirradiation light source and the quartz mold. The illuminanceimmediately below the quartz mold was 1 mW/cm² at a wavelength of 365nm.

(2-4) Mold Release Step

Next, the quartz mold was lifted under conditions of 0.5mm/s to separatethe quartz mold from the cured film (photocured product) made of thephotocurable composition. In this way, the photocured product wasobtained.

(3) Evaluation of Photocured Product

(3-1) Measurement of Mold Release Force

In this context, force required for separating the quartz mold from thephotocuried product (mold release), i.e., mold release force, in themold release step was measured using a compact tension/compression loadcell LUR-A-200NSA1 (manufactured by Kyowa Electronic Instruments Co.,Ltd.). The force was measured four times under the same conditions, andan average of values of the second and fourth measurements wascalculated as the mold release force of this Example. The results areshown in Table 1.

(3-2) TOF-SIMS Measurement

The surface of the photocured product obtained in this Example wassubjected to TOF-SIMS measurement. This TOF-SIMS measurement used aTOF-SIMS V apparatus manufactured by ION-TOF GmbH. The measurementconditions were set as follows:

Primary ion: Bi₃ ⁺, 0.3 pA (pulse current value)

Primary ion pulse frequency in sawtooth scan mode: 10 kHz (100 μs/shot)

Primary ion pulse width: approximately 0.8 ns

Measurement area: 500 μm×500 μm

The number of pixels in measurement area: 128×128

The number of scans: 32

Secondary ion detection mode: Positive

Gun for neutralization: ON

For the TOF-SIMS measurement, 3 measurement locations were arbitrarilyset for one sample and each measured. Then, the area of a mass spectrumpeak obtained at each measurement location was calculated as signalintensity. An average of the signal intensities of each peak wascalculated. The calculation results are shown in Table 1 describedlater.

Example 2

(1) Preparation of Photocurable Composition

Photocurable composition (a-2) of this Example (Example 2) was preparedin the same way as in Example 1 except that the amount of the fluorineatom-containing surfactant (F(CF₂)₆CH₂(OCH₂CH₂)₆OH) blended as componentC-1 in Example 1(1) was changed to 0.5 parts by weight.

The surface tension of the photocurable composition (a-2) was measuredin the same way as in Example 1 and consequently determined to be 27.5mN/m. Also, the viscosity of the photocurable composition (a-2) wasmeasured in the same way as in Example 1 and consequently determined tobe 6.77 cP.

(2) Preparation of Photocured Product

A photocured product was prepared in the same way as in Example 1 exceptthat photocurable composition (a-2) was used instead of the photocurablecomposition (a-1) of Example 1. Also, mold release force measurement andTOF-SIMS measurement were carried out in the same way as in Example 1.The results are shown in Table 1.

Comparative Example 1

(1) Preparation of Photocurable Composition

First, the following reagents and solvents were mixed:

(component A) 1,6-hexanediol diacrylate (manufactured by Osaka OrganicChemical Industry, Ltd.): 100 parts by weight

(component B) Irgacure 369 (manufactured by Ciba Japan Co., Ltd.): 3parts by weight

(component C-2) fluorine atom-containing surfactant: 2 parts by weight

Next, a mixed solution of components A, B and C-2 was filtered through a0.2 μm filter made of tetrafluoroethylene to obtain photocurablecomposition (b-1) of this Comparative Example (Comparative Example 1).

The surface tension of the photocurable composition (b-1) was measuredin the same way as in Example 1 and consequently determined to be 19.5mN/m. Also, the viscosity of the photocurable composition (b-1) wasmeasured in the same way as in Example 1 and consequently determined tobe 6.45 cP.

(2) Preparation of Photocured Product

A photocured product was prepared in the same way as in Example 1 exceptthat photocurable composition (b-1) was used instead of the photocurablecomposition (a-1) of Example 1. Also, mold release force measurement andTOF-SIMS measurement were carried out in the same way as in Example 1.The results are shown in Table 1.

TABLE 1 Comparative Example 1 Example 2 Example 1 Mold release force 128129 150 (mN/m) Signal intensity of 284006 176815 781835 C₂H₅O⁺ (m/z =45) Signal intensity of 35811 26990 1735277 C₃H₇O⁺ (m/z = 59)

The comparison of Example 1 with Comparative Example 1 demonstrated thatthe photocured product of Example 1 required smaller mold release forcethan that of Comparative Example 1 despite the same content of thefluorine atom-containing surfactant. In Example 1, the C₂H₅O⁺ ion(m/z=45) had signal intensity higher than that of the C₃H₇O⁺ ion(m/z=59). By contrast, in Comparative Example 1, the C₂H₅O⁺ ion (m/z=45)had signal intensity lower than that of the C₃H₇O⁺ ion (m/z=59).

In the comparison of Example 2 with Comparative Example 1, thephotocured product of Example 2 required smaller mold release force thanthat of Comparative Example 1 despite the lower content of the fluorineatom-containing surfactant than that of Comparative Example 1. In thephotocured product of Example 2, the C₂H₅O⁺ ion (m/z=45) had signalintensity higher than that of the C₃H₇O⁺ ion (m/z=59), as in Example 1.

Comparative Example 2

(1) Preparation of Photocurable Composition

Photocurable composition (c-1) was prepared in the same way as inExample 1 except that the fluorine atom-containing surfactant (componentC-1) was not contained therein in the photocurable compositionpreparation in Example 1(1).

The surface tension of the photocurable composition (c-1) was measuredin the same way as in Example 1 and consequently determined to be 31.2mN/m. Also, the viscosity of the photocurable composition (c-1) wasmeasured in the same way as in Example 1 and consequently determined tobe 6.80 cP.

(2) Preparation of Photocured Product

A photocured product was prepared in the same way as in Example 1 exceptthat photocurable composition (c-1) was used instead of the photocurablecomposition (a-1) of Example 1. Also, mold release force was measured inthe same way as in Example 1 and consequently determined to be 157 mN/m.

These results demonstrated that the photocured product prepared from thephotocurable composition free from the fluorine atom-containingsurfactant, as in Comparative Example 2, required larger mold releaseforce than that of the photocured product prepared from the photocurablecomposition containing the fluorine atom-containing surfactant.

Comparative Example 3

(1) Preparation of Photocurable Composition

Photocurable composition (c-2) was prepared in the same way as inComparative Example 1 except that the fluorine atom-containingsurfactant (component C-2) was not contained therein in the photocurablecomposition preparation in Comparative Example 1(1).

The surface tension of the photocurable composition (c-2) was measuredin the same way as in Example 1 and consequently determined to be 35.9mN/m. Also, the viscosity of the photocurable composition (c-2) wasmeasured in the same way as in Example 1 and consequently determined tobe 6.34 cP.

(2) Preparation of Photocured Product

A photocured product was prepared in the same way as in ComparativeExample 1 except that photocurable composition (c-2) was used instead ofthe photocurable composition (b-1) of Comparative Example 1. Also, moldrelease force was measured in the same way as in Example 1 andconsequently determined to be 158 mN/m.

These results demonstrated that the photocured product prepared from thephotocurable composition free from the fluorine atom-containingsurfactant, as in Comparative Example 3, required larger mold releaseforce than that of the photocured product prepared from the photocurablecomposition containing the fluorine atom-containing surfactant.

The results described above demonstrated that the photocured productthat contained the fluorine atom-containing surfactant, wherein theC₂H₅O⁺ ion (m/z=45) obtained by TOF-SIMS had signal intensity higherthan that of the C₃H₇O⁺ ion (m/z=59) required only small mold releaseforce.

In the results described above, the photocured product was obtainedwherein the ratio of the signal intensity of the C₂H₅O⁺ ion (m/z=45) tothat of the C₃H₇O⁺ ion (m/z=59) was 5 or more and 10 or less. However,it is only required that the signal intensity of the C₂H₅O⁺ ion (m/z=45)should be higher than that of the C₃H₇O⁺ ion (m/z=59). Specifically, thesignal intensity ratio is preferably 1.1 or more, more preferably 2 ormore.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2012-026144, filed Feb. 9, 2012, which is hereby incorporated byreference herein in its entirety.

1. (canceled)
 2. A photocurable composition for obtaining a photocuredproduct by irradiating the photocurable composition in contact with amold with light, the photocurable composition comprising: at least apolymerizable monomer; a photopolymerization initiator; and a fluorineatom-containing surfactant, wherein of secondary ion signals obtained bya surface analysis of the photocured product based on time-of-flightsecondary ion mass spectrometry, an intensity of a C₂H₅O⁺ ion signal ishigher than that of a C₃H₇O⁺ ion signal.
 3. A photocurable compositionfor obtaining a photocured product by irradiating the photocurablecomposition in contact with a mold with light, the photocurablecomposition comprising: at least a polymerizable monomer; aphotopolymerization initiator; and a fluorine atom-containing surfactantrepresented by:R₁ —x ₁—R₂ —x ₂—R₃  (1), wherein R₁ represents a perfluoroalkyl group,R₂ represents a divalent substituent containing ethylene oxide, R₃represents a polar functional group selected from an alkylhydroxylgroup, a carboxyl group, a thiol group, a pyridyl group, a silanolgroup, and a sulfo group, and x₁ and x₂ each represent a single bond ora divalent substituent, wherein a ratio of the fluorine atom-containingsurfactant to the photocured product is 0.001% by weight to 5% byweight, and wherein of secondary ion signals obtained by a surfaceanalysis of the photocured product based on time-of-flight secondary ionmass spectrometry, an intensity of a C₂H₅O⁺ ion signal is higher thanthat of a C₃H₇O⁺ ion signal.
 4. The photocurable composition accordingto claim 3, wherein the fluorine atom-containing surfactant isF(CF₂)₆CH₂(OCH₂CH₂)₆OH.
 5. A method for forming a photocured producthaving a predetermined pattern shape on a substrate, the methodcomprising: coating the substrate with a photocurable composition;contacting the photocurable composition with a mold; irradiating thephotocurable composition with light via the mold; and demolding the moldfrom the photocurable composition, wherein the photocured productcontains a fluorine atom-containing surfactant represented by:R₁ —x ₁—R₂ —x ₂—R₃  (1), wherein R₁ represents a perfluoroalkyl group,R₂ represents a divalent substituent containing ethylene oxide, R₃represents a polar functional group selected from an alkylhydroxylgroup, a carboxyl group, a thiol group, a pyridyl group, a silanolgroup, and a sulfo group, and x₁ and x₂ each represent a single bond ora divalent substituent, wherein a ratio of the fluorine atom-containingsurfactant to the photocured product is 0.001% by weight to 5% byweight, and wherein of secondary ion signals obtained by a surfaceanalysis of the photocured product based on time-of-flight secondary ionmass spectrometry, an intensity of a C₂H₅O⁺ ion signal is higher thanthat of a C₃H₇O⁺ ion signal.
 6. A method for producing a circuitsubstrate, the method comprising: applylng a photocurable compositiononto a substrate material; pressing a mold against the photocurablecomposition to form a pattern in the photocurable composition;irradiating the photocurable composition having the pattern with lightto prepare a cured product having the pattern; and releasing the moldfrom the cured product to form, on the substrate material, a circuitstructure based on the pattern in the cured product, wherein the curedproduct contains a fluorine atom-containing surfactant represented by:R₁ —x ₁—R₂ —x ₂—R₃  (1), wherein R₁ represents a perfluoroalkyl group,R₂ represents a divalent substituent containing ethylene oxide, R₃represents a polar functional group selected from an alkylhydroxylgroup, a carboxyl group, a thiol group, a pyridyl group, a silanolgroup, and a sulfo group, and x₁ and x₂ each represent a single bond ora divalent substituent, wherein a ratio of the fluorine atom-containingsurfactant to the photocured product is 0.001% by weight to 5% byweight, and wherein of secondary ion signals obtained by a surfaceanalysis of the photocured product based on time-of-flight secondary ionmass spectrometry, an intensity of a C₂H₅O⁺ ion signal is higher thanthat of a C₃H₇O⁺ ion signal.
 7. The method according to claim 6, whereinthe circuit substrate is a semiconductor device.
 8. A method forproducing a cured product having an elevation/depression pattern, themethod comprising: applylng a photocurable composition onto a basematerial; contacting a mold having an elevated/depressed surface withthe photocurable composition to form a correspondingelevation/depression pattern in the photocurable composition;irradiating the photocurable composition having the elevation/depressionpattern with light to prepare a photocured product; and releasing themold from the photocured product to produce the cured product having theelevation/depression pattern, wherein the photocured product contains afluorine atom-containing surfactant represented by:R₁ —x ₁—R₂ —x ₂—R₃  (1), wherein R₁ represents a perfluoroalkyl group,R₂ represents a divalent substituent containing ethylene oxide, R₃represents a polar functional group selected from an alkylhydroxylgroup, a carboxyl group, a thiol group, a pyridyl group, a silanolgroup, and a sulfo group, and x₁ and x₂ each represent a single bond ora divalent substituent, wherein a ratio of the fluorine atom-containingsurfactant to the photocured product is 0.001% by weight to 5% byweight, and wherein of secondary ion signals obtained by a surfaceanalysis of the photocured product based on time-of-flight secondary ionmass spectrometry, an intensity of a C₂H₅O⁺ ion signal is higher thanthat of a C₃H₇O⁺ ion signal.
 9. A method for forming a pattern, themethod comprising: applylng a photocurabie composition onto a basematerial; contacting a mold having an elevated/depressed surface withthe photocurabie composition to form a correspondingelevation/depression pattern in the photocurabie composition;irradiating the photocurabie composition having the elevation/depressionpattern with light to prepare a cured product having theelevation/depression pattern; and releasing the mold from the curedproduct to form the pattern in the cured product, wherein the curedproduct contains a fluorine atom-containing surfactant represented by:R₁ —x ₁—R₂ —x ₂—R₃  (1), wherein R₁ represents a perfluoroalkyl group,R₂ represents a divalent substituent containing ethylene oxide, R₃represents a polar functional group selected from an alkylhydroxylgroup, a carboxyl group, a thiol group, a pyridyl group, a silanolgroup, and a sulfo group, and x₁ and x₂ each represent a single bond ora divalent substituent, wherein a ratio of the fluorine atom-containingsurfactant to the photocured product is 0.001% by weight to 5% byweight, and wherein of secondary ion signals obtained by a surfaceanalysis of the photocured product based on time-of-flight secondary ionmass spectrometry, an intensity of a C₂H₅O⁺ ion signal is higher thanthat of a C₃H₇O⁺ ion signal.